1、Drawable→Bitmap
public staticBitmap drawableToBitmap(Drawable drawable) { Bitmap bitmap =Bitmap .createBitmap( drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), drawable.getOpacity() != PixelFormat.OPAQUE ?Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565); Canvas canvas = newCanvas(bitmap); //canvas.setBitmap(bitmap); drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight()); drawable.draw(canvas); returnbitmap; }
另附：
Resources resources =getResources(); //得到ResourcesDrawable drawable =resources.getDrawable(R.drawable.ic_launcher); //得到Drawable
Bitmap bitmap =drawableToBitmap(drawable);
iv.setImageBitmap(bitmap);2、从资源中获取Bitmap
Resources res=getResources();
Bitmap bmp=BitmapFactory.decodeResource(res, R.drawable.pic);3、Bitmap→byte[]
private byte[] Bitmap2Bytes(Bitmap bm){ ByteArrayOutputStream baos = newByteArrayOutputStream(); bm.compress(Bitmap.CompressFormat.PNG, 100, baos); returnbaos.toByteArray(); }
4、byte[]→Bitmap
private Bitmap Bytes2Bimap(byte[] b){ if(b.length!=0){ return BitmapFactory.decodeByteArray(b, 0, b.length); } else{ return null; } }
5、保存bitmap
static booleansaveBitmap2file(Bitmap bmp,String filename){ CompressFormat format=Bitmap.CompressFormat.JPEG; int quality = 100; OutputStream stream = null; try{ stream = new FileOutputStream("/sdcard/" +filename); } catch(FileNotFoundException e) { //TODO Auto-generated catch block e.printStackTrace(); } returnbmp.compress(format, quality, stream); }
6、将图片按自己的要求缩放
//图片源 Bitmap bm =BitmapFactory.decodeStream(getResources() .openRawResource(R.drawable.dog)); //获得图片的宽高 int width =bm.getWidth(); int height =bm.getHeight(); //设置想要的大小 int newWidth = 320; int newHeight = 480; //计算缩放比例 float scaleWidth = ((float) newWidth) /width; float scaleHeight = ((float) newHeight) /height; //取得想要缩放的matrix参数 Matrix matrix = newMatrix(); matrix.postScale(scaleWidth, scaleHeight); //得到新的图片 Bitmap newbm = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, true); //放在画布上 canvas.drawBitmap(newbm, 0, 0, paint);
相关知识链接：http://www.eoeandroid.com/thread-3162-1-1.html
7、bitmap的用法小结
BitmapFactory.Options option = new BitmapFactory.Options();
option.inSampleSize = 2; //将图片设为原来宽高的1/2，防止内存溢出
Bitmap bm = BitmapFactory.decodeFile("",option);//文件流
URL url = new URL("");
InputStream is = url.openStream();
Bitmap bm = BitmapFactory.decodeStream(is);
android:scaleType：
android:scaleType是控制图片如何resized/moved来匹对ImageView的size。ImageView.ScaleType /
android:scaleType值的意义区别：
CENTER /center按图片的原来size居中显示，当图片长/宽超过View的长/宽，则截取图片的居中部分
显示
CENTER_CROP / centerCrop按比例扩大图片的size居中显示，使得图片长(宽)等于或大于View的长
(宽)
CENTER_INSIDE / centerInside将图片的内容完整居中显示，通过按比例缩小或原来的size使得图片
长/宽等于或小于View的长/宽
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FIT_CENTER / fitCenter把图片按比例扩大/缩小到View的宽度，居中显示
FIT_END / fitEnd把图片按比例扩大/缩小到View的宽度，显示在View的下部分位置
FIT_START / fitStart把图片按比例扩大/缩小到View的宽度，显示在View的上部分位置
FIT_XY / fitXY把图片 不按比例 扩大/缩小到View的大小显示
MATRIX / matrix用矩阵来绘制，动态缩小放大图片来显示。
//放大缩小图片
public static Bitmap zoomBitmap(Bitmap bitmap,int w,int h){
int width = bitmap.getWidth();
int height = bitmap.getHeight();
Matrix matrix = new Matrix();
float scaleWidht = ((float)w / width);
float scaleHeight = ((float)h / height);
matrix.postScale(scaleWidht, scaleHeight);
Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix,
true);
return newbmp;
}
//将Drawable转化为Bitmap
public static Bitmap drawableToBitmap(Drawable drawable){
int width = drawable.getIntrinsicWidth();
int height = drawable.getIntrinsicHeight();
Bitmap bitmap = Bitmap.createBitmap(width, height,
drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
: Bitmap.Config.RGB_565);
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0,0,width,height);
drawable.draw(canvas);
return bitmap;
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}
//获得圆角图片的方法
public static Bitmap getRoundedCornerBitmap(Bitmap bitmap,float roundPx){
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(), bitmap
.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
final RectF rectF = new RectF(rect);
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return output;
}
//获得带倒影的图片方法
public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap){
final int reflectionGap = 4;
int width = bitmap.getWidth();
int height = bitmap.getHeight();
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
Bitmap reflectionImage = Bitmap.createBitmap(bitmap,
0, height/2, width, height/2, matrix, false);
Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height/2),
Config.ARGB_8888);
Canvas canvas = new Canvas(bitmapWithReflection);
canvas.drawBitmap(bitmap, 0, 0, null);
Paint deafalutPaint = new Paint();
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canvas.drawRect(0, height,width,height + reflectionGap,
deafalutPaint);
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0,
bitmap.getHeight(), 0, bitmapWithReflection.getHeight()
+ reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);
paint.setShader(shader);
// Set the Transfer mode to be porter duff and destination in
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
// Draw a rectangle using the paint with our linear gradient
canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
+ reflectionGap, paint);
return bitmapWithReflection;
}
}